By driving 8 mph faster than Bob, John can make a 230 mile trip in one half hour less.How fast does Bob drive on the trip? Round your answer to the nearest mile per hour

Answer:   57 mphStep-by-step explanation:Let b represent Bob's speed on the trip. Then his time is ...   time = distance/speed   Bob's time = 230/bThen John's speed is b+8, and his time is ...   John's time = 230/(b+8)The difference of their times is 1/2 hour:   Bob's time - John's time = 1/2   230/b -230/(b+8) = 1/2 . . . substitute the expressions for time   460(b+8 -b) = b(b+8) . . . . . multiply by 2b(b+8)   b^2 +8b -3680 = 0 . . . . . . .put in standard form   (b +4)^2 -3696 = 0 . . . . . . . add 16-16 to complete the square   b = -4 +√3696 ≈ 56.795 . . . solve for positive bBob's drove about 57 mph on the trip.